Please cite this article in press as: Feitosa VP, et al. Impact of hydrophilicity and length of spacer chains on the bonding of functional monomers. Dent Mater (2014), http://dx.doi.org/10.1016/j.dental.2014.06.006 ARTICLE IN PRESS DENTAL-2407; No. of Pages 7 d e n t a l m a t e r i a l s x x x ( 2 0 1 4 ) xxx–xxx Available online at www.sciencedirect.com ScienceDirect jo ur nal home p ag e: www.intl.elsevierhealth.com/journals/dema Impact of hydrophilicity and length of spacer chains on the bonding of functional monomers Victor P. Feitosa a,b,* , Salvatore Sauro b,c , Fabricio A. Ogliari d , Aline Oliveira Ogliari d , Kumiko Yoshihara e , Cesar H. Zanchi d , Lourenc ¸o Correr-Sobrinho a , Mário A. Sinhoreti a , Américo B. Correr a , Timothy F. Watson b , Bart Van Meerbeek e a Piracicaba Dental School, State University of Campinas, Piracicaba, Brazil b King’s College London Dental Institute, Biomaterials, Biomimetics and Biophotonics (B3) Group, London, United Kingdom c Biomaterials and Minimally Invasive Dentistry – Departamento de Odontologia, Facultad de Ciencias de laSalud, Universidad CEU-Cardenal Herrera, Valencia, Spain d Federal University of Pelotas, Pelotas, Brazil e KU Leuven – BIOMAT, Department of Oral Health Sciences, KU Leuven (University of Leuven), Leuven, Belgium a r t i c l e i n f o Available online xxx Keywords: Functional monomer Adhesion Durability Micro-permeability Hydrophilicity Self-etch adhesive a b s t r a c t Objectives. 10-Methacryloyloxy-decyl-dihydrogen-phosphate (10-MDP) is currently consid- ered as one of the most effective functional monomers for dental bonding, this in part thanks to its long and relatively hydrophobic spacer chain, adequately separating the polymeriz- able from the phosphate functionalities. This study compared functional monomers with different spacer chains’ length and hydrophilicity to 10-MDP on their dentin and enamel bonding performance. Methods. Atomic absorption spectroscopy (AAS) was used to characterize the chemical inter- action. Micro-tensile bond strength (TBS) and fractographic analyses were performed after 24 h and one year. Confocal micro-permeability and SEM nanoleakage assessments were also undertaken. The tested functional monomers were 2-MEP (2-carbon spacer), 10-MDP (10-carbon), 12-MDDP (12-carbon), MTEP (high hydrophilic polyether spacer chain) and CAP- P (intermediate hydrophilic ester spacer). Results. AAS revealed clear differences (p < 0.05) in monomer-calcium salt formation in this order: 12-MDDP = 10-MDP > CAP-P > MTEP > 2-MEP. The highest initial dentin TBS was obtained using 10-MDP or 12-MDDP. After 1-year aging, a significant drop (p < 0.05) in TBS was observed for the adhesives with MTEP (enamel and dentin), 2-MEP (enamel) and CAP-P (enamel). MTEP presented the highest micro-permeability, while 2-MEP, CAP-P and MTEP showed increased nanoleakage after aging. ∗ Corresponding author at: Área de Materiais Dentários, FOP-Unicamp, Av. Limeira 901, Piracicaba 13414-903, SP, Brazil. Tel.: +55 19 21065345. E-mail addresses: victorpfeitosa@hotmail.com, feitosavpf@gmail.com (V.P. Feitosa). http://dx.doi.org/10.1016/j.dental.2014.06.006 0109-5641/© 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.